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The
human body's largest organ is the skin. Skin protects body
tissues against injuries and helps regulate body temperature by
making the pores larger or smaller. The
nerves in skin receive
the stimuli that are then interpreted by the brain as touch,
heat, and cold. Skin is composed of three layers: epidermis,
dermis, and subcutaneous fatty tissue.
The
interface between the epidermis and dermis is extremely
irregular and consists of a succession of papillae, or
fingerlike projections, which are smallest where the skin is
thin and longest in the skin of the palms and soles. The
papillae of the palms and soles are associated with elevations
of the epidermis, which produce ridges that are the basis for
fingerprint identification.
Subcutaneous fatty tissue is the deepest layer of the skin. It
is composed of connective tissue, blood vessels, and fat cells.
This layer binds the skin to underlying structures, insulates
the body from cold, and stores energy in the form of fat.
The
skin forms a protective barrier against the action of physical,
chemical, and bacterial agents on the deeper tissues and
contains the special end organs for the various sensations
commonly grouped as the sense of touch. Through the activity of
its sweat glands and blood vessels, it is important in
maintaining body temperature. One square inch
(6.5 square centimeters) of skin contains up to 4.5 m of blood
vessels, which have as one of their functions the regulation of
body temperature. The skin varies in thickness from 0.5 mm on
the eyelids to 4 mm or more on the palms and soles.
More about your skin:
The
typical body has between 20 ft2 to 22 ft2
of surface area which serves as a radiator for releasing heat
via radiation to lower the body temperature or as an absorber to
take in radiant energy to raise the body temperature. The skins
emissivity is around 0.97 which makes it almost perfect as a
radiator and absorber.
"There is no normal temperature but a range over which
temperature fluctuates and changes."
Dr. Tim Lowenstein
"...your skin
temperature varies parabolically from 83 deg F. (28.2 C) at an
ambient temperature of 49 deg F. (9.5 C) to 98 deg F. (37.2 C)
at an ambient temperature of 95 deg F (35 C)."
Dr. K.R. Koehler College Physics for Students of Biology and
Chemistry, University of Cincinnati
Suggested reading:
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